88 CLINICAL APPLIED ANATOMY. 



this region. Of these the two commonest are fracture of the 

 internal epicondyle, and a transverse fracture just above the level 

 of the olecranon fossa. 



That part of the inner condyle which is outside the capsule of 

 the joint is styled the epicondyle (or sometimes the epitrochlea). 

 From its prominence it is greatly exposed to injury and is 

 frequently detached by violence. When separated, the flexor 

 muscles arising from it tend to drag it downwards and somewhat 

 forwards. The close proximity of the ulnar nerve to the 

 posterior aspect of the process renders it liable to injury or to be 

 involved in callus. 



The transverse fracture is generally the outcome of indirect 

 violence and is only transverse so far as its lateral direction is 

 concerned, for it is oblique from behind downwards and forwards 

 when its antero-posterior axis is examined. Thus the displace- 

 ment of the fragments is easily explained. The lower end of the 

 upper fragment comes forward and apparently downwards and 

 will even injure the brachial vessels and the median nerve lying 

 in front of it. In some cases it may actually perforate the skin 

 above the crease of the elbow. The lower fragment, together 

 with the bones of the forearm, is carried backwards and upwards 

 by the action of the triceps aided by the pull of the biceps and 

 brachialis anticus. Thus the arm, measured from the acromion 

 process to the external condyle, will be shortened. 



Fractures of the Ulna alone. There is only one common 

 form of fracture of the ulna alone, and that is a fracture of the 

 olecranon process, which may be broken either by direct or in- 

 direct violence. It is a fairly common lesion owing to the 

 exposed position of the process and the strength of the muscles 

 which act upon it. 



By direct violence the fracture may be either near the tip, or 

 some little distance lower down where there is a slight narrowing, 

 at the spot where the bony projection joins the shaft. 



In indirect violence that is, by the action of the triceps as 

 a rule only the tip of the process, or the olecranon epiphysis is 

 dragged off. 



